Fluorocarbon silicone compositions

ABSTRACT

ORGANOSILANCES AND SILANOLS OF THE FORMULA   (X)(3-A)-SI-CH2-CH2-RF-CH2-CH2-SI(-R)A(-X)(3-A)   AND SILOXANES OF THE FORMULA   (O)((3-A-B)(1/2))-SI(-R)A-CH2-CH2-RF-CH2-CH2-SI(-R)A)-   (O)((3-A-B)(1/2))   ARE DISCLOSED. EXAMPLES OF SUCH COMPOUNDS INCLUDE   CL-SI(-CH3)2-CH2-CH2-(CF2)6-CH2-CH2-SI(-CH3)2-CL AND   CF3-CH2-CH2-SI(-CH3)(-(O/2)-CH2-CH2-(CF2)6-CH2-CH2-   SI(-CH3)(-(O/2)-CH2-CH2-CF3   CERTAIN POLYMERS ARE PARTICULARLY USEFUL FOR MAKING REVERSION RESISTANT SILOXANE RUBBERS AND RESINS.

3,647,740 FLUOROCARBON SILICONE COMPOSITIONS Lorne A. Loree, Ogden R.Pierce, and Yung Ki Kim, Midland, Mich., assignors to Dow CorningCorporation, Midland, Mich. N Drawing. Continuation-impart ofapplication Ser. No. 749,577, Aug. 2, 1968. This application June 23,1970,

Ser. No. 57,022

Int. Cl. C08g 51/04 U.S. Cl. 260-37 SB Claims ABSTRACT OF THE DISCLOSUREOrganosilanes and silanols of the forumla Certain polymers areparticularly useful for making reversion resistant siloxane rubbers andresins.

This application is a continuation-in-part of application Ser. No.749,577, filed Aug. 2, 1968, now US. Pat. 3,542,830.

This invention relates to novel fluorocarbon-containing siliconecompositions. In one aspect the invention relates to polysiloxaneelastomers having high temperature stability.

Organosiloxane elastomers, such as dimethylpolysiloxane rubber, areknown to retain their elastomeric properties over a wide temperaturerange and because of this property have found application in a varietyof environments. Siloxane rubber which contains fiuorinated aliphaticradicals attached to the silicon atom, has recently been made available.This elastomer is resistant to swelling when in contact with automotivefuels, lubrieating oils and the like.

One problem remaining in this area of elastomer technology is that ofreversion or degradation of the polymer structure when the elastomer isconfined in certain environments for long periods of time. For example,when used as sealants in aircraft fuel tanks some polysiloxaneelastomers revert i.e., depolymerize, to the extent that theirelastomeric properties are completely lost. In this type of use,retention of the elastomeric properties is critical and a high degree ofreversion resistance is necessary.

It is an object of the invention to provide novel useful organosiliconcompounds.

Another object of the invention is to provide a reversion resistantorganosilicon elastomer which has the tem- United States Patent 03,647,740 Patented Mar. 7, 1972 "ice perature stability and solventresistance of known polysiloxane materials.

According to the invention there are provided silanes of the formula RaRa Additionally, the invention provides siloxanes having at least oneunit of the formula r r (II) 0 siorrzontntonzouts i0 2 Xh X5 2 in whichX, R an R, are as defined above; a has a value of 0 to 3 inclusive; bhas a value of O to 3 inclusive; the sum of all a and b values being notgreater than 5; any remaining siloxane units being of the formula inwhich Z is a hydrogen atom, the hydroxy, a hydrolyzable group, or anorganic radical attached to the silicon atom through an SiC linkage; andc has a value of from O to 3 inclusive.

The invention also includes polysiloxane elastomers comprising the abovedefined siloxane homopolymers or icopolymers in combination with afiller. The elastomers of the invention can contain any suitable fillersuch as metal oxides, for example, titania, zinc oxide, ferric oxide andthe like; siliceous materials, for example, clay, diatomaceous earth,crushed quartz and silicas, for example, fume silica, and silicaaerogel. Carbon black is another suitable filler. If desired, theelastomers can also contain other materials such as compression setadditives, pigments, oxidation inhibitors and other additives commonlyused in organopolysiloxane rubbers.

The fillers can be employed in any desired amount ranging from 5 to 200parts filler per parts polymer. The amount of filler will vary with thetype of filler and the properties desired in the finished elastomer. Insealant applications, it is preferred that the elastomer contain from 10to 50 parts filler per 100 parts polymer.

The elastomers of the invention can be vulcanized by any of the knownmethods for vulcanizing organosiloxane rubber. One method comprisesheating the compounded elastomer with an organic peroxide such asbenzoyl peroxide, tertiary-butyl perbenzoate, dicumyl peroxide, andtertiary-butyl-peracetate. Preferably, the peroxides are employed inamounts from 0.1 to 10 weight percent based on the amount of siloxanepolymer in the formulation. Another method of vulcanization is toincorporate oletinic radicals in the polysiloxane which providecrosslinking sites for the vulcanization process. As shown in theexamples, this can be done forming a copolymer in accordance with theinvention where Z is a vinyl or other olefinic radical.

Another method comprises mixing the instant polysiloxanes containingalkenyl groups with SiI-I containng siloxanes and a platium catalyst orby mixing the instant polymers containing SiOH groups with such room temperature active cross-linkers as alkoxy silanes, acetoxy silanes or SiHcontaining siloxanes with the appropriate metal catalysts such as tinsalt of carboxylic acids.

In the silane compositions (1) of this invention, X can be anyhydrolyzable group such as halogen atoms; such as fluorine, chlorine,and bromine; hydrocarbonoxy groups such as methoxy, ethoxy,octadecyloxy, allyloxy, cyclohexyloxy, phenoxy, tolyloxy, benzyloxy,

acyloxy groups such as acetoxy, propionyloxy, benzoyloxy, cyclohexyloxy,and

ketoxime groups such as ON=C(CH and amine groups such as -NH -N(CH andsulfide groups such as --SCH and the nitrile group, the isocyanategroup, sulfate groups such as II o carbamate groups such as -OOCNHCH-OOCN(CH and OOCN(C H and groups such as -N(CH and --ON(C3H7)2.Hydrolyzable group as used in this specification is defined as a groupwhich is removed from the silicon atom by reaction with water atroom-temperature.

R can be any monovalent hydrocarbon radical such as alkyl radicals suchas methyl, ethyl, propyl, isopropyl, butyl, pentyl, isopentyl,neopentyl, hexyl, octyl, dodecyl, octadecyl, 3-methylheptyl,fi-butyloctadecyl, tertiary butyl, myricyl and 2,2-diethylpentyl;alkenyl radicals such as, vinyl, allyl, he'xenyl, butenyl, 3-octenyl,4,9- octadecadienyl and 4-nonenyl; alkynyl radicals such as propynyl,heptynyl, butynyl, decynyl; alkenynyl radicals such as l-penten-3-ynyl,Z-ethyl-l-buten-B-ynyl; cycloaliphatic radicals such as, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, propylcyclohexyl,2,4-dimethylcyclopentyl, cyclohexenyl, bicyclo{3.1.0}hexyl,tricyclo{3.2. 'l.1 }-5-nonenyl, spiro{4.5}decyl,dispiro{4.1.4.2}-1-tridecenyl, decahydronaphthyl, 2,3-dihydroindyl and1,2,3, 4-tetrahydronaphthyl; aryl radicals such as phenyl, tolyl, xylyl,3-ethylphenyl, xenyl, naphthyl, anthracyl, pentacenyl,3,4-methylethylphenyl, 9,9'-bifluoryl and 4-m-terphenyl; and aralkylradicals such as 2-phenyl-octy1, 3- methyl-2-(4-isopropylphenyl)heptyl,benzyl, 2-ethyltolyl, 2-ethy1-p-cymyl, diphenylmethyl,4,5-diphenylpentyl, 2- phenylethyl and 2-phenylpropyl.

When R is an unsaturated group it is best to add it to the siliconsubsequent to the formation of the structure. This can be done, forexample, by reacting an unsaturated Grignard reagent (i.e. vinylmagnesium bromide) with SiCl. The same or different R groups can beattached to the same silicon atom.

R can also be any radical of the formula RCH CH 4 in which R' is aperfluoroalkyl radical such as CF C F s rz, 1o 21 3)2 OF CF CF- aSubstituents in which R contains from 1 to 10 inclusive carbon atoms arepreferred.

In addition, R can be any halohydrocarbon radical in which the halogenis chlorine, bromine or iodine, such as aliphatic groups, for example,chloromethyl, 3-ch1oropropyl, 3,3,3-trichloropropyl and chlorooctadecyl;aromatic groups, for example, dichlorophenyl, tetrabromoxenyl,tetrachlorophenyl, alpha,alpha,alpha-tribromotolyl and iodonaphthyl;cycloaliphatic groups, for example, chlorocyclohexyl, bromocyclopentyland chlorocyclohexenyl and aralkyl groups, for example chlorobenzyl,beta-(chlorophenyl)ethyl, beta-(iodophenyl) ethyl andbeta-(bromopherryDpropyl. R radicals, both hydrocarbon andhalohydrocarbon, of from 1 to 18 inclusive carbon atoms are preferred.

The R, radical can be any suitable perfluoroalkylene radical for example-'OF C F -C F 7 14,

4 o a a (CF02 including any perfluorocycloalkylene radical, such as C F20 F3 -0 F C F- \C F 062 R, radicals of from 1 to 20 inclusive carbonatoms are preferred and, for reasons of economy, perfluoroalkyleneradicals of from 1 to 6 inclusive carbon atoms are especially preferred.

The silanes (I) of the invention are best prepared by reacting silanesof the formula nsixa.

with an alpha,omega-perfluoroalkene (CH CHR;CH=CH in the presence of aplatinum catalyst, such as chloroplatinic acid, or a peroxide catalystin the conventional manner for adding SiH compounds to compounds havingterminal CH =CH groups. The peroxide-catalyzed addition, for example,using di-t-butylperoxide, is preferred because of the high yieldobtained. The olefinic intermediates are prepared by addition ofethylene to BrB Br followed by dehydrobromination of the resultingadduct. Ethylene addition to BrR Br where R; contains at least 4 carbonatoms is especially desirable since a high yield of CH CHR CH=CH isobtained. Bromine addition to perfiuoro-beta-oxa or thiaglutaric acidsprovides the dibromide precursor for the compounds of the inventionwhich contain C--OC or C-S-C bonding.

The silanols of the invention (i.e. where X is the hydroxy group) arebest prepared by hydrolyzing the corresponding hydrolyzable silanesunder neutral conditions by any of the methods well-known in the art.The preferred method of silanol preparation is by hydrolysis of thosecompounds in which X is a methoxy group.

The siloxanes (II) of the invention can be prepared by partial orcomplete hydrolysis or cohydrolysis of the above-defined silanes byconventional means, or by cohydrolysis of the above silanes with silanesof the formula Z.,SiX

where Z, X and c are as defined above. The particular method chosen forthe hydrolysis or cohydrolysis can vary widely depending upon the natureof the substituent groups on the silicon atom. Thus, there are nocritical conditions other than the well-known methods for bydrolyzingand cohydrolyzing silanes.

Another method of preparing the siloxanes of the invention is by theaddition of CH GHR CH=CH to siloxanes containing SiH groups in thepresence of platinum catalysts. The conditions for carrying out thisreaction are the same as those normally employed in the addition ofSiH-containing siloxanes to olefins.

As described above, the siloxanes can be homopolymers or they can becopolymers having various perfiuoroalkylene-containing siloxane units.In addition the siloxanes of the invention can contain siloxane units ofthe formula where c has a value of from 0 to 3 inclusive. These includedunits of the type SiO ZSiO Z SiO and Z SiO The same or different Zgroups can be bonded to the same silicon atom.

Z can be a hydrogen atom, a hydroxyl group, any of the above definedhydrolyzable groups (X) or an organic radical attached to the siliconthrough an Si-C linkage, such as any of the monovalent hydrocarbonradicals, preferably of 1 to 18 inclusive carbon atoms, specificallyshown for R above; divalent hydrocarbon radicals, for example methylene,dimethylene, CH CH=CHCH and octadecamethylene; arylene radicals, forexample, phenylene, xenylene, tolylene, xylylene and naphthylene; andcycloalkylene radicals such as cyclohexylene and cyclopentylene. Z canalso be any halohydrocarbon radical, such as described with respect to Ror the above described R'CH CI-I radical.

Also included within the scope of the invention are siloxanes asdescribed above which have olefin-containing siloxane units, such asZSiO H (1H2 The methylvinylsiloxane units are especially preferred.These olefin-containing siloxane units are usually present in amount inthe range of from 0.1 to mole percent to provide cross-linking sites inthe polymer.

The siloxanes of the invention are fluids, resins and elastomericmaterials. The resin forms a hard film and can be used as a coatingcomposition. The elastomers have particularly utility as sealants inhigh temperature environments and have a high resistance to degradationupon exposure to radiation and the fluids are useful as lubricants.

The following examples are illustrative of the invention which isdelineated in the claims.

EXAMPLE 1 (A) A solution of 106.2 g. (0.3 mole) of CHFCH (C1 CH=CH 528g. (3.0 moles) of c1 CF CHgCH S iH and 3 g. of di-t-butylperoxide washeated under reflux. As the reaction proceeded the reaction temperatureincreased from about 104 C. to 107 C. At the end of 72 hours of reflux,gas chromatographic analysis of the reaction mixture showed the presenceof the di-adduct as the major component. Distillation of the reactionmixture gave, after recovery of the excess silane, 192 g. of

which had a boiling point of 160 to 162 C./1 mm. Hg, melting point of 41to 42 C., and a neutralization equivalent of 351 (calc. 353).

(B) CHFCH(CF CH=CH and Cl (CH- )SiH were reacted in a similar manner toobtain a high yield of which had a boiling point of to 131 C. at 0.65mm. Hg and a melting point of 51.5 to 525 C.

(C) CH =CH(CF ).-,CH==CH and Cl SiH were reacted in a manner similar to(A) and (B) to give a high yield of Cl SiCH CH (CF CH CH SiCl which hada RP. of to 152 C./.75 mm. Hg and a melting point of 62 C.

EXAMPLE 2 Into a stirred solution of 12 g. of sodium bicarbonate in 150ml. of water, there was added slowly a solution of 4 g. of Cl Si(CH )CHCI-l (CF CH CH Si(CH )Cl in 100 ml. of diethylether at room-temperature.After the addition was complete, the mixture was stirred for about 15minutes at room-temperature. Then the ether layer was separated, washedwith aqueous hydrochloric acid, twice with water, and dried. Ether wasevaporated at roomtemperature, and the resulting solid hydrolyzate wastaken into 10 ml. of ethylene glycol dimethylether. Four drops of acatalyst consisting of a solution of 1 mol of tetramethyl guanidine inthree mols of trifiuoroacetic acid were mixed into the solution. Thesolvent was then removed at room-temperature. The resulting partiallycured resin was further cured in an air circulating oven at 100 C. for96 hours to give a hard, tough, smooth-surfaced hydroxyl end-blockedresinous polymeric composition of the unit formula EXAMPLE 3 About g. Ofwas taken into 100 ml. of diethylether and hydrolyzed as described inExample 2 above. The ether insoluble, partially condensed solidhydrolyzate was removed by filtration, and the ether layer wasseparated, washed with aqueous (5%) hydrochloric acid, twice with water,and dried. The ether solution was evaporated at room-temperature to avolume of 10 ml. Two drops of a solution of tetramethylguanidine intrifiuoroacetic acid (1:3 mols) were added and mixed with the ethersolution. The solvent was evaporated from the resulting solution atroom-temperature. The resulting partially cured resin was heated at 150C. in an air-circulating oven for 0.5 hour to yield a hard strong thinfilm of [O SiCH CH (CF CH CH SiO EXAMPLE 4 Following the procedureoutlined in Example 3 above, a mixture of 1.5 g. of

Cl Si(CH )CH CH (CF CH CH Si(CH )Cl and 2 g. of Cl SiCH CH (CF CH CHSiCl was hydrolyzed, and the ether soluble portion of the hydrolyzateswas co-condensed to give a clear, strong, thin film of the copolymerhaving the formula 7 EXAMPLE Following the procedure outlined in Example2, a mixture of2g. of

and 4 g. of

.C1 Si (CH CH CH (CF CH CH Si(CH C1 was hydrolyzed and co-condensed toyield a tough, strong and flexible film of the copolymer Following theprocedure outlined in Example 2 above, a mixture of 4 g. of

r a CF CH CH SiCHgCHflCF MCHgCHgSiCH CH CFg and 3g.

of CI (CH )SiCH CH (CF CH CH Si(CH )C1 was hydrolyzed and co-condensedto yield a flexible, tough and smooth copolymeric resin of about 2 to 3mm. in thickness of the formula CH3 CH3 Ou SiCH CHflCFmcH GH iom H2 CH2CH3 (5H2 CFa a osiomomwmuomomsio Ha a] EXAMPLE 7 A mixture of 1 42 g.(0.55 mole) of CF CH CH SiHCl 24 g. (0.06 mole) of CH CH(CF CH=CH and 1g. of ditert-butyl peroxide was heated at 110 to 120 C. under anatmosphere of dry nitrogen. At the end of about 40 hours of heating, thereaction was stopped, and the mixture was distilled to yield 42 g. (78%yield) of B.P. 192 to 193 C. (0.3 mm. Hg), M.P, 81 to 82 C.

When this compound is hydrolyzed and condensed according to theprocedure of Example 2, a siloxane of the unit formula 8 was obtainedhaving a boiling point of 182 C. (0.3 mm.) and a melting point of from61 to 62 C.

EXAMPLE 9' The hydrolyzate arising from the hydrolysis of 27 g.

was condensed at C. using 4 drops of a solution oftetramethylguanidine-trifluoroacetic acid. When the viscosity of thepolymer reached about 10,000 cs. (after about 20 min), a solution of 50m1. of

Ill/1e (CH CHSD NH in 100 ml. of ethylene glycol dimethylether was addedat once to the polymer while stirring at 100 C. The reaction mixture wasstirred at 100 C. for 22 hours, and then stripped to remove the solvent.The resulting prodnot formed two layers. The upper layer was decanted,and teh viscous liquid polymer (the bottom layer) was taken into about20 m1. of ether. The ethereal solution was washed with about 10% aqueoushydrochloric acid, saturated aqueous sodium bicarbonate, water anddried. After evaporation of ether, the resulting olefin-containingpolymer was placed under about 0.1 mm. Hg pressure at 15 0 C. for 15hours to remove any volatile material. The viscous fluid polymer wasfound to crosslink well. The molecular weight of the polymer was about10,700 and it was of the formula CH CH CH3 CH CH =CHS iO S iCH2CH (CF2)uCH2CHZS iO S iCH=CH2 Ha H2 H2 H3 Hz 1112 Fa F EXAMPLE 10 About 55 g.of the hydrolyzate of CH CH3 C1SlCHgOH2(CF2)6CH2CH2 iC1 H2 H2 H2 (L3H:CF: JFa

was taken into a solution of 50 ml. of CH CN and 0.5 ml. of water. Dryammonia was bubbled into the homogeneous solution for about 30 sec. Themixture was then placed in a shaker at room-temperature for 12 hours.The resulting mixture was placed under about 0.75 mm. Hg pressure atroom-temperature for 4 hours, then at 100 C. for 4 hours. The resultingpolymer was viscous fluid having a molecular weight of about 7,000 and ahydroxy content of 0.39 Weight percent of the unit formula CH; 011 SiCH3CHg(C Fz)uCHzCHzS i O H3 CH CH2 CH F JF x 9 EXAMPLE 11 A mixture of25 g.. of the hydrolyzate of CH C1SiCHZCHg C FDGGHZCHZS i-Cl H2 2 H. CH$1 3 (BF;

and 0.45 g. of

CHFCHSiCIfl was heated at 100 C. While stirring under a stream of drynitrogen. After one hour of heating, three drops of a solution oftetramethylguanidine in trifluoracetic acid (1:3) was introduced and theheating (100 C.) were continued, while stirring, for 2 hours. Theresulting polymer was kept under about 1 mm. Hg pressure at 100 C. forabout 16 hours. The polymer was an elastomeric material. The molecularweight was found to be about 90,000. The F and H N.M.R. and infraredspectra of the polymer were in agreement with the following polymerstructure:

containing in the polymer chain small amounts of the vinyl crosslinkingsites as:

-sit- 1511:! (A) Following the procedure described above, the followinghigh consistency polymer was also prepared.

CFa

containing about 1 mole percent of the vinyl crosslinking sites as 10(B) The following polymer was obtained in like manner,

containing about 1 mole percent of the vinyl crosslinking sites as wasdissolved in an equal volume of tetrahydrofuran. 5 drops of a solutionof tetramethylguanidine in trifluoroacetic acid (1:3) were added and thesolution was refluxed for 3 hours. About 60 g. of [(CH Si] NH was addedto the reaction mixture and the mixture was heated under reflux for 20hours. The solvent and excess were removed under vacuum, and theresulting product was taken into ether. The ethereal solution was washedwith a 5% aqueous hydrochloric acid, saturated sodium bicarbonatesolution and dried. After removal of ether under vacuum atroom-temperature, the viscous fluid was stripped at 150 C. under about0.1 mm. Hg pressure to yield a clear viscous fluid. The viscosity of thefluid was about 150 cs. The elemental analysis and spectral data were inagreement with the polymer structure.

Distillation of the fluid prepared above gave having a HP. C. (0.75mm.), n 1.3775 and a higher viscosity fluid.

EXAMPLE 13 About 15 g. (0.0212 mole) of CH CH ClS iCHzCHg(C F2)oCHzCHgSli Ci was hydrolyzed using an aqueous sodium bicarbonateethersystem. The dried ethereal solution containing monomer diol was stirredat 100 C. overnight under a stream of dry nitrogen. The resultingviscous fluid was taken into ether, and the ethereal solution was washedwith saturated so- CH CH a a dium bicarbonate, a aqueous hydrochloricacid, water, OHSICHZCHKCFmOHZGHZfiOH 5 and then dried. After removal ofether, the resulting H2 CH2 prepolymer was condensed using 5 drops of asolution CH3 CH2 of tetramethyl guanidine in trifiuoroacetic acid (1:3)at g g 100 C. The polymerization was conducted under vacuum F3 F3 withstirring. The prepolymer turned to a gummy elas Was added t0 9 mole) oftomer within minutes. The polymerization was continued overnight. Theresulting copolymer was an elasa)2 2 3 2 z)2 tomeric gum of the averageformula ?H3 ?H3 CH3 CH3 (3H3-S[iCH2CI'I2(CF2)aCI'IgCHgfil-O-Si-O-SiCH2OH2(CF2)6CH2CHzSiO (6H: CH2 H2H2 Hz (5H; (5H; H: I Hz (EH2 CF: CF; F3 CFa F 3 JJFz Fa u containingabout sites as:

1 mole percent of the vinyl crosslinking H H CH2 Following the procedureoutlined above, the same molar amounts of CH3 CH; (333 I l H2oraouzornsion and nos iomormormomomsion SlCH2OH2(GF2)fl H2 H2 H2 H CH2Ha (:JHZ H2 10 ("3H2 (5H2 H2 (31-12 H2 H2 B Fa on X were reacted with0.23 mole of cm y on,

CF CH CLhSiCl to yield the copolymer of the average formula CH3 CH3 CH3CH3 CH3 iCHgCHflCF2)aCHzCH iO-i-O-SiCHgCHACFQsCH CH iO CH2 H H2 CH2 OH;H, CH2 Hz (311, H; F; lF CF F3 (1F3 n EXAMPLE 14 which contained about 1mole percent of vinyl cross- A mixture of 31 g. (0.046 mole) of linkingSites CH3 CH; ([3173 noshomomwrmonzcrnsion CH1 CH2 Hz H, but 51. IF; i8.2 g. 0.023 mole) of H1 0H3 EXAMPLE 15 CFa0F2 Fz Fz H20H2S iCh When CH=CH(CF O(CF CH=CH and and 0.16 (1 mole percent) f Cl SiH are heated inthe presence of di-t-butylperoxide CFZGHZCHzSiCh the following productis obtained:

H C1 SiCH CH (CF O-(CF CH CH SiCl UJHZ This product can be hydrolyzed bythe method set 13 forth in Example 2 to yield a strong flexible polymerof the unit formula:

KMn04 HOOCOFgSCFgCO OH ClgSlCHgCHgC F SC FgCHgCHgSiClg Hydrolysis andcondensation of this silane as shown in Example 15 produces a siloxaneof the unit formula OSiCHgCHzC FgCHgCHzSiO Ha a EXAMPLE 17 WhenC1Sl(CH2CHZOFa)CH2CH2(C F2)6CH2CH2(C F CH CHz)S|iCl is hydrolyzed inaqueous sodium bicarbonate solution and condensed by the addition oftetramethyl guam'dine in trifluoroacetic acid solution, the followingpolymer is obtained:

CF; CF;

EXAMPLE 18 When a solution of 1 mole CH ==CH(CF CH=CH- 10 moles of $1FQCHZCHZSiH and a catalytic amount of di-t-butylperoxide is heated underreflux, the reaction mixture, after distillation of excess silane,contains as a major component the following product:

When this material is hydrolyzed and condensed with tetramethylguanidine-trifluoroacetic acid solution a siloxane of the unit formula.5 .5 or ofizomsiomomwmmomcmslromomom H H I is obtained.

14 EXAMPLE 19 \A high visocosity polymer fluid of the followingcomcomposition Me Me (CH S1O S i CHgCHg (C F2) aCHgCHz i O Si (0139 F Fl;

was prepared as shown in Example 12.

This polymeric material had a viscosity of 856 cs. when measured at 77-F. To determine its suitability as a lubricant, the material was testedby the 4-ball method in which a one-half inch steel ball is rotatedagainst three stationary one-half inch steel balls and the length andwidth of the scar on each stationary bearing is measured. Testconditions and results are tabulated below:

4-BALL TE ST CONDITIONS Scar Speed Time Load diam.

Temp. F.) (r.p.m.) (hrs.) (kg.) (mm.)

The results show the polymer fluid to be a highly eflective lubricant.

EXAMPLE 20 (A) parts by weight of a hydroxyl-endbloeked copolymercontaining 99.5 mol percent of and 0.5 mol percent of units werecompounded with 40 parts by weight of fume silica (filler), 17 parts byweight of CF CH CH (CH )SiO fluid (plasticizer), 2 parts by Weightferric oxide (stabilizer) and 0.5 weight percent di-tertiarybutylperoxide (catalyst). This formulation was cured at 200 C. for 8 hours.

(B) 100 parts by weight of a hydroxyl-endblocked copolymer of 98 molpercent of units and 2 mol percent of units were compounded with thesame materials in the same amounts as was formulation (A). Thiselastomer was also cured at 200 C. for 8 hours.

The physical properties of the elastomers are given below:

Percent swell in toluene Tear strength,

Elonga- Shore A tion,

durometer p.s.i. percent lb. /in.

1 Measured according to the procedure of ASTM D-624-54, Die B.

This data demonstrates the elastomeric properties and low swellcharacteristics of rubber formulated in accordance with the invention.

EXAMPLE 21 Tensile, Elastomer butyl tin diacetate (catalyst), parts byweight carbon black (stabilizer), and 10 parts by weight fume silica(filler) which had been treated with the cyclic trimer oftrifluoropropylrnethylsiloxane. Evaluation of this sealant is describedbelow.

Both sealants were compounded on a three-roll mill and allowed to cureby exposing them to the atmosphere for one week at room temperature.

In order to evaluate reversion resistance in a fuel tanktype ofenvironment both samples were placed in a covered kettle to which areflux condenser was attached. Three liters of jet fuel (JP4),containing paraffin wax to raise its boiling point, were introduced intothe vessel along with 3 liters of air. The temperature of the fuel wasmaintained at 450 F. Each week the fuel was changed following this sameprocedure. The samples were maintained in this high temperature fuelenvironment for several weeks.

Visual observation of the samples each week showed the sealant of theinvention to become progressively stronger while retaining itselastomeric properties. The conventional sealant remained serviceablebut became softer and weaker as the test continued. At the end of weeksthe sealant of the invention was in excellent condition. After 16 weeksit was noted that water had leaked into the reflux condenser and had rundown into the fuel vessel. The samples were examined and it was foundthat the trifluoropropylmethylsiloxane elastomer WaS degraded to theextent that substantially all elastomeric properties were lost; thematerial had softened to a tarry consistency. The elastomer formulationIbased on the perfluoroalkylene-bridged polymer was not noticeablyaffected.

Cured rubber after being maintained After cure at 200 C. for 8 hours at250 C. for 24 hours Shore A Tensile, Elongation, Shore A Tensile,Elongation, Sample durometer p.s.i. percent durometer p.s.i. percent washydrolyzed and condensed by the procedure outlined in Example 2 to yielda hydroxyl endblocked polymer of That which is claimed is: 1. A siloxanehaving at least one unit of the formula X is the hydroxy or ahydrolyzable group,

R is a hydrogen atom, a monovalent hydrocarbon radical, a monovalenthalohydrocarbon radical in which the halogen is Cl, Br or I, or a RCH CHradical where R is a perfluoroaliphatic radical,

R; is a perfiuoroalkylene radical, a perfluorocycloalkylene radical or aperfiuoroalkylene radical or a perfluorocycloalkylene radical containingone or more C- O-C or C-SC linkages, said R, radical containing no morethan 20 carbon atoms, and each a has a value of from 0 to 3 inclusive,and

b has a value of from 0 to 3 inclusive, the sum of all a and b valuesbeing not greater than 5; any remaining siloxane units being of theformula Z SlO 2:1

in which: Z is a hydrogen atom, the hydroxy or a hydrolyzable group, amonovalent hydrocarbon radical, a divalent hydrocarbon radical, amonovalent halohydrocarbon radical in which the halogen is Cl, Br or Ior a R'CH CH radical wherein R is a perfluoroaliphatic radical, and chas a value of from to 3 inclusive.

2. The siloxane of claim 1 wherein R is selected from the groupconsisting of monovalent hydrocarbon radicals of from 1 to 18 inclusivecarbon atoms and RCH CH radicals wherein R is a perfluoroalkyl radicalof from 1 to inclusive carbon atoms.

3. The siloxane of claim 2 wherein Z is a monovalent hydrocarbon radicalof from 1 to 18 inclusive carbon atoms.

4. The siloxane of claim 3 wherein R; is a perfluoroalkylene radical offrom 1 to 20 inclusive carbon atoms.

5. The siloxane of claim 4 wherein R is a perfiuoroalkylene radical offrom 1 to 6 inclusive carbon atoms.

6. The siloxane of claim 1 wherein R is a perfluoroalkylene radicalcontaining one or more CO-C or CSC linkages.

7. The siloxane of claim 6 wherein R is a F: F: radical.

8. The siloxane of claim 6 wherein R; is a l. l, radical.

9. The siloxane of claim 1 wherein R, is a perfluorocycloalkyleneradical.

10. The siloxane of claim 1 wherein R is a perfluorocycloalkyleneradical containing one or more C-O-C or C--SC linkages.

11. The siloxane of claim 1 in which essentially all of the units are ofthe formula 12. The siloxane of claim 1 having the formula O SiCH CH (CFcn cn sio 13. A siloxane in accordance with claim 5 consistingessentially of units of the formula having vinyldimethylsiloxy terminalgroups.

14. A siloxane in accordance with claim 1 consisting essentially ofunits of the formula in units.

15. The siloxane of claim 1 consisting essentially C F; 0 a

2 H2 S iCHzCHg(C rmomomslio units and H6 CH3 C F; (EH. .5... r. o .5...

units.

16. A siloxane elastomer comprising (1) a polysiloxane in whichessentially all of the units are of the formula II: I a 3-a-b ZZRfCHQOHZSIi O3 2 Kb Kb 2 in which:

X is the hydroxy or a hydrolyzable group;

R is independently selected from the group consisting of the hydrogenatom, monovalent hydrocarbon radicals, monovalent halohydrocarbonradicals in which the halogen is Cl, Br or I, and RCH CH radicals inwhich R is a perfiuoroaliphatic radical;

R; is selected from the group consisting of perfluoroalkylene radicals,pertluorocycloalkylene radicals and perfluoroalkylene orperfluorocycloalkylene radicals containing one or more C-O-C or C-SClinkages, said R, radical containing no more than 20 carbon atoms, andeach a has a value of from O to 3 inclusive,

b has a value of from 0 to 3 inclusive, the sum of all a and b valuesbeing no greater than 5; any remaining siloxane units being of theformula in which:

Z is a hydrogen atom, the hydroxy or a hydrolyzable group, a monovalenthydrocarbon radical, a divalent hydrocarbon radical, a monovalenthalohydrocarbon radical in which the halogen is Cl, Br or I or a radicalwherein R is a perfiuoroaliphatic radical, and c has a value of from 0to 3 inclusive; and (2) a filler.

17. The siloxane elastomer of claim 16 wherein said filler is present inan amount in the range of from 5 to 200 parts by weight per parts byweight of said polysiloxane.

18. The siloxane elastomer of claim 17 wherein R is selected from thegroup consisting of monovalent hydrocarbon and halohydrocarbon radicalshaving from 1 to 18 inclusive carbon atoms and R'CH CH radicals inwhich:

R is a perfluoroalkyl radical having from 1 to 10 inclusive carbonatoms;

R; is a perfluoroalkylene radical having from 1 to 20 inclusive carbonatoms; and

Z is a monovalent hydrocarbon or halohydrocarbon radical having from 1to 18 inclusive carbon atoms.

19. The siloxane elastomer of claim 18 wherein R is a perfluoroalkyleneradical having from 1 to 6 inclusive carbon atoms.

20. A composition vulcanizable to an elastomer comprising thepolysiloxane and filler of claim 17 further characterized as includingfrom 0.1 to 10 weight percent based on the weight of the siloxane of anorganic peroxide.

21. The siloxane elastomer of claim 16 wherein R; is a perfluoroalkyleneradical of from 1 to 20 inclusive carbon atoms containing one or moreCO-C or CSC linkages.

22. The siloxane elastomer of claim 16 wherein R; is a 20perfluorocycloalkylene radical of from 1 to 20 inclusive 25. Thesiloxane elastomer of claim 16 consisting carbon atoms. essentiallyof 1) 100 parts by weight of a copolymer 23. The siloxane elastomer ofclaim 16 wherein R is a containing from 90 to 99.9 mol percent of unitsof the perfluorocycloalkylene radical of from 1 to 20 inclusive formulacarbon atoms containing one or more C-C or CH3 CH3 O-SC linkages.

24. The siloxane elastomer of claim 16 consisting fi essentially of (1)100 parts by weight of a copolymer of H, CH1 from 90 to 99.9 molepercent of units of the formula B (3H2 F3 Fg CH3 CH8 and from 0.1 to 10mol percent of units of the formula O. SiCH CHz(CFghCHzCH SiQs E H2 H1$10 i i CF; CF; H4

and (2) 10 to 50 parts by weight of filler.

and from 0.1 to 10 mole percent of units of the formula References CitedUNITED STATES PATENTS 0 3,458,554 7/1969 Haluska 260-448.2. 3,542,83011/1970 Kim et a1. 260-4482,

I s40 DONALD E. CZAJA, Primary Examiner M. I. MARQUIS, AssistantExaminer US. (:1. X.R. F a

252-495 R; 26018 s, 45.7 R, 45.75 R, 46.5 E, 46.5 G, and 2 from 5 to 200parts by weight of filler. 448-2 D: 825 R

